Pre-Employment Exams A Spinal Focus

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Pre-Employment ExamsA Spinal Focus

• Spinal Intrinsic Risk Factors
• Dr David McGrath 2008
• www.drdavidmcgrath.com.au

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Questions

• What are They ?
• How Bad are they ?
• Can we find them ?
• Should we find them ?

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Possible Risk Factors

• Current Pain
• Old Injuries
• Congenital or Acquired Deformities
• Anthropometric Extremes
• Age
• Gender
• Level of Fitness
• Strength and Robustness
• Imaged Pathology

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Assessing the Risk(hypothetical non specific
risk factor OR17 )
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Deductions

• With a prevalence of 10, and an absolute risk
  contribution of ½,we need approximately 100
  examinations to reduce, the adverse employment
  outcomes by 50 (by not employing or effective
  risk management )

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Detection(sensitivity 80, specificity 77 )
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The Risk Adjusted Company(Perfect
InterventionAll those identified with risk
factor prevented from bad outcome NNT2)First
number indicates employees with risk
factorSecond number indicates, employees without
risk factor
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Risk Intervention Effectiveness (Compared
to natural company history with 50 bad
outcome)NNT1/(6/8-4/8)4
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Company after Realistic Intervention (NNT4)
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Non-Hiring Option(28 at-risk diagnosed and not
hired, leading to 72 remaining )(8 with risk
factor excluded, 20 non risk employees excluded
)(72 remaining employees, 2 have risk factor,70
dont )50 of the 21 and 5(1/2) of 704 have
bad outcome
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After Hiring another 28 in 139 exams total
(excluding 39 candidates, only 11 of which have
the risk factor, while 28 dont )
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Comparing Outcomes
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Remember

• Odds Ratio17 (ie relatively high)
• Detection se80 sp77 (ie good)
• NNT4 Risk Intervention (ie good)
• Interventions for 28 (20 no risk)
• Exams139 with rejection strategy
• Rejected applicants without risk28 (20 of
  candidates)
• Rejected applicants with risk11 (8 candidates,
  but 10 prevalence)

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Summary

• With Detection/Risk Intervention strategy, we
  examine 100 employees,20 less bad outcome, and
  intervene on 28 employees (20 of which dont
  have risk)
• With Detection/Dont hire policy, we have, 25
  less bad outcome, and examine, 139 prospective
  employees, reject 20 with no risk

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Things To Consider

• Cost of Exams
• Stigma to rejected applicants
• Cost of interventions
• Cost and Significance of Bad Outcomes

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Armed Forces

• Cost of Training High
• Cost of Intervention High
• Cost of Bad Outcome High
• Cost of Exams relatively Cheap
• Stigma of Rejection ??

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Trial Of Fire

• Relax initial entry criteria
• Boot Camp survival test (many compo claims arise
  from this period)
• Chance of re-entry if fitness or strength is
  limiting factor
• Not generally available to high end, service
  skill occupations
• e.g. pilots, aircrew

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Spines

• Whats Worth Looking For ?
• Whats the best detection method ?
• Whats the cost/benefit ? For either the non hire
  or risk intervene option
• What are technical, legal, ethical, social
  limitations

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Recurrent Back Pain

• LBP gt30 days during past year, increased risk
  OR4.8 long lasting BP
• OR3.3 Leg pain
• OR5.9 Medical Discharge
• (Hestbaek 2005) n1711 Danish Military Recruits
  Conscription
• Generally this factor is thought to have good Se,
  but poor Sp. Also poor Reliability.

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Muscle Strength

• Strength testing alone has no predictive value
  for work place injuries
• (Harbin G 2005) n2,482 Food factory study
• Likely discrimination against women, certain
  ethnic groups, and handicapped, using the
  Detect/Dont hire policy

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Job Matching

• With employees who had matching physical
  capacity, to inherent requirements of job,
  incidence of injuries was 3
• With employees, without matching capacity,
  incidence of injuries was 33
• NNT3 in this instance
• (Harbin G 2005) Factory Workers
• 38 physical theoretical mismatch in an industry
  with a high incidence of LBP
• (Pedersen DM 2005) Utah Mechanics

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Scoliosis etc

• Kyphosis/lordosis (side plane)
• Skewed pelvis
• Scoliosis (frontal plane)
• Rotoscoliosis (front, axial)
• Sparse reliable, valid data, on occupation
  outcome measures
• OR3.0 LBP adolescents (Kovacs 2005)

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Congenital Malformations

• Dysraphism (usually detected at birth)
• Dysegmentalism (sacralisation, lumbarisation,acces
  sory articulations )
• No valid data

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Disc Disease

• Isolated Disc Resorption (significant loss of
  disc height)
• Bulges
• Prolapses
• V.E.P Osteophytic Outgrowth
• Sparse, unreliable data

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Scheuermanns Disease

• The definition, has relaxed from the original
  thoracic kyphosis deformity (to a number of
  vertebral end plate deformities)
• No reliable /valid data on risk for various
  occupations

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Isthmic Spondylolitheses

• No reliable /valid data on occupational risk
• Overall risk perceived to be low

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Intervertebral Canal Pathology

• Congenital or Acquired Spinal Stenosis
• Spinal Cord Pathology
• Other Spinal canal Pathology
• No Reliable or Valid data for occupations

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Muscular Imbalance

• Signs of muscular Irritability
• Associated geometry deformity
• Associated poor dynamic range of specific joints
• Low reliability (inter or intra observer )
• No valid data
• Assume similar to scoliosis ? (OR3 LBP)

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Body Mass Index

• Mild positive association, increasing for longer
  pain duration
• Positive association, unlikely to be causal, as
  correlation disappears with monozygotic twins
• (Leboeuf Yde 1999 ) n29,424 twins
• Probable, weight increase with chronicity

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Co-Morbidity

• Positive association of LBP and headache and
  asthma
• (Hestbaek L 2006 ) n9,567
• Age cohort 12-22
• The presence of two other disorders increased the
  probability of LBP considerably
• Frail subgroup drops from 60 to 25 at age 22.
• a common origin should be considered

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Smoking

• Association between smoking and LBP
• (Leboeuf-Yde 1999 )
• The association is not likely to be causal, as
  there is no dose response relationship, and
  disappears with twin study

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LBP Adolescents

• Strong correlation between adolescent LBP and
  adult LBP OR4
• 8 year follow up study
• N10,000
• Dose Response Relationship
• (Hestbaek L 1999 Danish Study)
• Future Research, should focus on young
  Population

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LBP Schoolchildren

• LBP not related to heredity
• Scoliosis related to heredity
• Strong association between pain in bed or upon
  arising and LBP. OR13
• LBP and Scoliosis OR3
• LBP and Leg length difference OR1.3
• LBP and sport practice more than 2/week OR1.2
• (Kovacs FM 2005 Spanish cross sectional study
  n16,394)

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LBP and Schoolchildren(continued)

• No Association for LBP and alcohol intake,
  cigarette smoking, BMI, book transport method,
  hours of leisure sitting.
• Point prevalence (7 day period) was 17 boys and
  33 girls.

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Spondylosis

• Not valuable as a diagnoses
• The population attributable risk is around 15,
  as an association with LBP, and thus can be
  viewed as an intrinsic risk factor.

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Gender

• Women more at risk of developing chronic LBP
• OR2.65 Military Physical training
• OR2.49 Military Occupation
• OR2.91 Off Duty Activities
• OR0.05 Sporting Activity
• OR3.17 Overall
• (Strowbridge NR 2005) n928 new cases
• English Military Prospective Study

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Intelligence and Education

• In one study, LBP in military recruits,
  intelligence protects OR5, while having parents
  with high education was slightly negative OR1.9
  (Hestbaek L 2005)

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Multiple Minor Risk Factors

• A little bit of this, a little bit of that
• Do risk factors, add or compound ?
• A slightly bad neck and a crook back
• No valid studies

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What to Do ?

• History (detailed or cursory )
• History Exam (detailed or cursory )
• History Exam XR (whole spine or Lx)
• History Exam XR Further Imaging
• History Exam Functional Matching
  (quantitative or qualitative job/physical
  characteristics )
• None of the Above

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Strategies for Less than Ideal
Math's

• Identify Risk Factors as an awareness promoting
  exercise and Institute an early reporting system
• Consider, job matching trial (recall Harbin
  NNT3)
• and/or
• Aggressive early intervention (secondary
  prevention)
• Avoiding, costly intervention on false positives,
  non effective intervention on true positives, or
  the stigma of non-hire (true or false positive)
• Employment exams as an Insurance policy, against
  fraudulent or excessive claims ?

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Things To Re-Consider

• Cost of Exams
• Stigma to rejected applicants
• Cost of interventions (primary or secondary)
• Cost and Significance of Bad Outcomes
• Potential Role of Exams as Part of Employee Care
  Program

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Questions Lively Discussion

• Are other areas of the body better off ?
• How reliable/valid are cardiovascular risk
  factors ?
• How to better integrate intrinsic and extrinsic
  risk factors ?
• Most diseases are multi-risk generated ?